Electron beam welding requires high accuracy in positioning the beam over the joint due to the small diameter of the electron beam, from 0.010" to perhaps 0.050" depending upon the power supplied by the beam. The greater the power, the larger the diameter of the beam in a typical machine. Deep penetration of the electron beam also requires precise alignment of the welding beam and the joint.
In order to satisfactorily weld the three segments which comprise the drill bit, it is necessary that the electron beam, as it moves in relation to the drill bit, always take a path which passes through the abutting faces of the joint being welded. Heretofore in the welding of drill bits, because of variations in dimension of one segment from another due to manufacturing tolerances, and because of differences in the clamping effect of the means for clamping the segments together, it has been found that imperfect and partially welded joints have resulted due to the fact that the path of the electron beam did not pass through the full surface represented by the plane of the abutting faces of the parts being welded. It was found that whereas the beam passed through a plane which passed through the vertical axis of the turntable upon which the parts were mounted, the parts themselves, due to manufacturing imperfections and clamping differences, did not present their abutting faces in a plane which passed through the vertical axis. The plane of the abutting faces could be tilted to one side or the other of the vertical axis of the turntable. The result was that only a partial welding of the surfaces was effected, leading to the necessity to reweld or completely reject the partially welded drill bits. The old methods for aligning the beam to the plane of the abutting joint were time-consuming and crude and resulted in many welds which did not pass inspection.